Knee Exam

Introduction

In order to make sense of the joint examination, you must have an understanding
of functional anatomy. Without this, the provocative maneuvers used to define
the precise nature of the joint problem will make no sense. By gaining an appreciation
for the basic structures and functioning of the joint, you’ll be able to “logic”
your way thru the exam, even if you can’t remember the eponym attached to each
specific test! The complete examination of the knee or shoulder is usually performed
in the setting of pain, decline in function or other focal complaint.


Observation

    1. Make sure that both knees are fully exposed. The patient should be in either
      a gown or shorts. Rolled up pant legs do not provide good exposure!
    2. Watch the patient walk. Do they limp or appear to be in pain? When standing,
      is there evidence of bowing (varus) or knock-kneed (valgus) deformity? There
      is a predilection for degenerative joint disease to affect the medical aspect
      of the knee, a common cause of bowing.
    3. Assessment is better performed with a bare-foot patient.

Varus Knee Deformity, more marked on the left leg.

    1. Make note of any scars or asymmetry. Chronic/progressive damage, as in
      degenerative joint disease, may lead to abnormal contours and appearance.
      Is there obvious swelling as would occur in an effusion? Redness suggesting
      inflammation?

  1. Is there evidence of atrophy of the quadriceps, hamstring, or calf muscle
    groups? Knee problems/pain can limit the use of the affected leg, leading
    to wasting of the muscles.

While both legs have well developed musculature, the left calf and hamstring are bulkier than the right.

  1. Look at the external anatomy, noting structures above and below the knee
    itself:

    1. Patella
    2. Patellar tendon
    3. Quadriceps/Hamstring/Calf muscles
    4. Medial and lateral joint lines.
    5. Femur and Tibia
    6. Tibial tuberosity

Palpation and Examination for Degenerative Joint Disease:

    1. If the knee is injured, start by examining the unaffected side. This allows
      for comparison and relaxes the patient as you are not performing maneuvers
      that cause discomfort from the outset.
    2. Ask the patient to bend the knee, gauging whether they can fully extend
      and flex. This is referred to as their active range of motion. Full extension
      is 0 degrees, full flexion ~ 140.

Knee Flexion (Left) and Extension (Right)

    1. Place one hand on the patella. Note any warmth, which if present, would
      suggest inflammation. Grasp the ankle or calf with your other hand and gently
      flex the knee. Note the extent to which you can flex and extend the knee,
      referred to as its passive range of motion. Also, using the hand on the patella,
      feel for crepitus. This is a crackling/grinding sensation that occurs with
      movement. If present, it’s indicative of degenerative joint disease (DJD).
      It reflects a loss of the normal smooth movement between the articulating
      structures (femur, tibia, and patella). DJD is suggested by the presence of
      pain with activity that gets progressively more limiting over time. There
      may be a history of antecedent injury, which caused the inciting damage to
      the articulating surface. And co-existent damage to ligaments or menisci may
      also be present (see below). When defining the extent of DJD, the knee is
      broken into 3 compartments: Medial, central, and lateral. DJD can occur in
      any or all regions. The precise location of the DJD can be hard to determine
      on examination and is more accurately defined via x-rays.

X-Ray of Normal Knee (Left) and Knee With DJD (Right)

  1. If any of the above maneuvers elicits pain, stop and note at what point
    in the range of motion this occurs.

Tests for an effusion:

An effusion is the accumulation of fluid within the joint space. If there
is a large collection, the knee will look swollen. Lesser amounts of fluid can
be a bit more subtle. Patient’s symptoms are often related to whatever caused
the fluid to accumulate in the first place. The effusion itself makes the knee
feel as if it’s somewhat unstable or floating and may limit range of motion.
Effusions resulting from inflammatory arthritis (e.g. infection, gout, rheumatoid
arthritis) are associated with other signs of inflammation, including: warmth,
redness, pain with any movement.

Large Effusion, Right Knee.

Ballotment (Patella Tap Test) – Helpful if the effusion is large

  1. Slightly flex the knee which is to be examined.
  2. Place one hand on the supra-pateallar pouch, which is above the patella and communicates with the joint space.
    Gently push down and towards the patella, forcing any fluid to accumulate in the central part of the joint.
  3. Gently push down on the patella with your thumb.
  4. If there is a sizable effusion, the patella will feel as if it’s floating and “bounce” back up when pushed down.

Balloting the Left Knee.

Milking (helpful for detecting small effusions)

  1. Gently stroke upwards along the medial aspect of the patella, pushing fluid
    towards the top and lateral aspects of the joint.
  2. Gently push on the lateral aspect of the joint. If there’s a small effusion,
    the fluid which was milked to the lateral aspect will be pushed back towards
    the medial area of the joint, causing the medial skin to bulge out slightly.

Technique for Milking an Effusion

Inflammatory Arthritis and Effusions:

Intense inflammatory processes within the joint space can also cause an effusion.
Infection, gout, and rheumatoid arthritis are a few of the conditions that can
lead to an inflammatory arthritis (IA) and effusion. The joint and overlying
skin is usually warm and red. In addition, there is significant pain with any
active or passive movement. The more intense the inflammation, the more severe
the pain. Identifying the precise cause of IA is critical as it directs the
clinician towards the best treatment, limiting permanent damage to the joint.
This usually requires aspiration and examination of the joint fluid. Inflammatory
fluid has a high white cell count and should contain other clues as to its origin
(e.g. gout –> crystals on microscopy; infection –> bacteria on gram
stain and culture; etc). Fluid from those with degenerative effusions has relatively
few white cells. Clinically, patients with DJD have few signs of inflammation
and some degree of preserved range of motion (ROM). Historical information also
helps distinguish DJD from IA. DJD is usually slowly progressive while those
with IA more often have an acute presentation. Additionally, those with IA may
have characteristic patterns of recurrence (e.g. great toe MTP in gout, MCPs
of hands in RA), systemic symptoms, suggestive joint deformities (e.g. ulnar
deviation of the hands in RA), and particular radiographic changes. Of course,
it’s possible to have elements of both IA and DJD. DJD, for example, can result
from joint damage that occurred secondary to past episodes of gout or infection.

Gouty Inflammation of Metatarsal-Phalangeal Joint, Left Great
Toe


Specific Maneuvers for the Knee Exam

Tests for Meniscal Injury

Normal anatomy and function: The menisci sit on top of the tibia
and provide a cushioned articulating surface between the femur and tibia. Symptoms
occur when a torn piece interrupts normal smooth movement of the joint. This
can cause a sensation of pain, instability (“giving out”) or locking in position.
Injury may also cause swelling. If the meniscus has been injured and no longer
adequately covers the tibia, damage can occur to the underlying bone, leading
to degenerative arthritis.

Anatomy of Menisci, Right Knee (patella has been removed).

Joint Line Tenderness:

    1. Have the patient slightly flex their knee. The knee is slightly flexed
      when performing all of the functional tests that are described below. This
      positions the joint such that other stabilizing elements do not interfere
      with the structure that is being tested.
    2. Define the joint space along its lateral and medial margins. The joint
      line is perpendicular to the long axis of the tibia.
    3. Gently palpate along first the medial and then the lateral margins. Pain suggests that the
      underlying meniscus is damaged.

Palpation Along Lateral (picture on left) and Medial (picture on right) Joint Lines. The Joint Line is Marked by Purple Line.

  1. Note that only a portion of the meniscus lies near the joint line. The
    remainder of the meniscus cannot be assessed with this technique.

Assessment of Medial Joint Line Tenderness Assessment of Lateral Joint Line Tenderness

McMurray’s Test

    1. When examining the right knee, place your left hand so that your middle,
      index, and ring fingers are aligned along the medial joint line.
    2. Grasp the foot with your right hand and fully flex the knee.
    3. Gently turn the ankle so that the foot is pointed outward (everted). Then
      direct the knee so that it is pointed outward as well (valgus stress).
    4. While holding the foot in this everted position, gently extend and flex
      the knee. If there is medial meniscal injury, you will feel a “click” with
      the hand on the knee as it is extended. This may also elicit pain.

Simulated McMurray’s Test With Foot Everted (left). Close-up (right) Reveals How This Maneuver Streeses The Medial Meniscus.


 

McMurray’s Test: Assessment Of Medial Meniscus Demonstrated In Picture On Left, Lateral Meniscus In Picture On Right.

  • Now, return the knee to the fully flexed position, and turn the foot inwards
    (inversion). Then direct the knee so that it is pointed inward as well (varus
    stress).
  • Place the index, middle, and ring fingers of your left hand along the lateral
    joint line.
  • Gently extend and flex the knee. If the lateral meniscus has been injured,
    you may feel a “click” with the hand palpating the joint line. You
    may also elicit pain.
  • Technically, eversion of the foot is not part of the test. The actions show and indeed the test is to rotate the leg either medially (internally) for testing of the lateral meniscus or laterally (externally) for the medial meniscus. Varus and Valgus forces at the knee open or close the joint line. Also, the test is aimed at the posterior portion of the menisci. Orthopedic surgic`gfal confirmation of McMurray’s test has shown that it can be less than 75% accurate. Beware of false positives or negatives.

McMurray’s Test

Appley Grind Test

    1. Have the patient lie on their stomach.
    2. Grasp one ankle and foot with both of your hands and gently flex the knee to ninety degrees. Hold
      the patients leg down by gently placing your leg over the back of their thigh.

Appley Grind Test

  1. Push down gently while rotating the ankle back and forth.
  2. This maneuver places direct pressure on the menisci. If injured, it will cause pain.
  3. Test the opposite leg in the same fashion.

Tests for Injury to the Ligaments

Normal anatomy and function

The ligaments are very strong tissues that connect bone to bone. In the knee,
they assure stability and correct alignment. There are 4 main ligaments in the
knee: Medial collateral (MCL), lateral collateral (LCL), anterior cruciate (ACL)
and posterior cruciate (PCL). The medial and lateral ligaments provide stability
in response to medial and lateral joint stress. The cruciate ligaments limit
anterior and posterior movement of the femur on the tibia and limit the degree
to which the knee can rotate. Injury usually requires significant force. Following
a ligamentous injury, there is generally acute pain, swelling and the injured
person will often report hearing a “pop” (the sound of the ligament tearing).
After the acute swelling and pain have dissipated, the patient may report pain
and instability (sensation of the knee giving out) during any maneuver that
would expose the deficiency created by the damaged ligament (e.g. rotation,
during which there is nothing to “check” the movement of the femur on the tibia).

Anatomy of Ligaments, Right Knee (Patella Has Been Removed).

The following are common mechanisms of injury for each of the major ligaments:

  1. ACL: Most commonly injured when the foot is planted while extreme rotational
    force is applied (e.g. a cleated foot caught in the turf while an athlete attempts
    to rotate towards that side). The ACL may also be injured from a direct force
    on the lateral knee while the foot is planted.
  2. PCL: Much less commonly injured
    then the ACL. Posterior force on the tibia (e.g. the tibia striking against
    the dashboard in a motor vehicle accident) can lead to disruption.
  3. LCL: Direct
    force on the medial aspect of the knee while the foot is planted.
  4. MCL: Direct
    force on the lateral aspect of the knee while the foot is planted.

Given the
forces required to tear a ligament, menisci are often damaged at the same time.
It is also possible to tear more then one ligament at once. When testing any
ligament, remember the following:

  1. Always begin your exam with the asymptomatic
    knee. This gives you some sense of the individual normal degree of laxity. That
    is, the “tightness” of everyone’s ligaments varies somewhat. By working on their
    unaffected side, you will define “normal.” It also helps to generate a sense
    of trust between you and the patient.
  2. If you’re unsure as to whether there is really an abnormality, check back
    and forth between the normal and abnormal sides. This will enhance your ability
    to identify differences.
  3. It can be difficult to examine patients with large joints, particularly if you
    have small hands!
  4. Detecting subtle abnormalities takes lots of practice,
    particularly if you don’t have a great sense for the range of normal.
  5. It can be extremely difficult to examine the acutely injured knee. Movement often
    causes significant pain. The patient is understandably apprehensive and will
    use surrounding muscles to prevent movement. This inability to relax is a normal
    response and may limit the extent of your exam. It may be necessary to simply
    wait until the acute inflammation resolves (with rest, elevation, anti-inflammatory
    medications, and time) before being able to perform an accurate exam.

Specifics of Ligament Testing

Medial Collateral Ligament

    1. Slightly flex the right knee.
    2. Place your left hand along the lateral aspect of the knee.
    3. Place your right hand on the ankle or calf.
    4. Push steadily inward with your left hand while supplying an opposite force
      with the right.

 

Stressing the MCL

  • If the MCL is completely torn, the joint will “open up” along the medial
    aspect.

Simmulated Torn MCL–Note How Joint Line Opens Up Along Medial Aspect

  1. Reverse hand position to assess the left knee.
  2. Additionally, palpation along the course of the ligament may also elicit
    pain if it has been injured.

Medial Collateral Ligament

Lateral Collateral Ligament

    1. Slightly flex the right knee.
    2. Place your right hand along the medial aspect of the knee.
    3. Place your left hand on the ankle or calf.
    4. Push steadily outward with your right hand while supplying an opposite
      force with the left.

Stressing the LCL

    1. If the LCL is completely torn, the joint will “open up” along the lateral
      aspect.

Simmulated Torn LCL–Note How Joint Line Opens Up Along Lateral Aspect

  1. Reverse hand position to assess the left knee.
  2. Additionally, palpation along the course of the ligament may also elicit
    pain if it has been injured.

Lateral Collateral Ligament Testing

Alternative method for stressing the medial lateral collateral ligaments:

  1. Extend the patient’s knee and cradle the heel between your arm and body.
    The knee should be slightly flexed.
  2. Place your index fingers across the medial and lateral joint lines.
  3. Using your body and index fingers, gently provide first medial and then lateral stress to the joint.

Stressing the MCL and LCL


Technique for stressing the MCL and LCL

Anterior Cruciate Ligament

Lachman’s Test

    1. For testing the right leg, grasp the femur just above the knee with your
      left hand and the tibia with your right.
    2. Flex the knee slightly.
    3. Pull up sharply (towards your belly button) with your right hand while
      stabilizing the femur with the left. The intact ACL will limit the amount
      of A/P sheer that you can achieve. The intact ACL is described as providing
      a firm end point during Lachman testing.

Stressing the ACL

  1. If the ACL is completely torn, the tibia will feel unrestrained in the
    degree to which it can move forward (see above for image of simulated ACL
    tear).
  2. Compare this to the other leg, reversing your hand position.
  3. The patient must be able to relax their leg for this test to work. If they
    cant, then compensatory muscles will limit the degree of motion, making it
    very difficult to assess the integrity of the ACL.
  4. If the thigh is too big in circumference (or your hand too small) to stabilize,
    you can perform the Lachman’s test with the leg hanging off the side of the
    table (see picture below).

Variation On Lachman’s Test For Patients With Large Legs.


Lachman’s Test Positive Lachman’s Test

Anterior Drawer Test

    1. Have the patient lie down, with the right knee flexed such that their foot
      is flat on the table.
    2. Gently sit on the foot. Grasp below the knee with both hands, with your
      thumbs meeting along the front of the tibia.
    3. Gently pull forward, gauging how much the tibia moves forward in relation
      to the femur. The ACL, if intact, will provide a discrete end point.

Stressing the ACL

    1. If the ACL is completely torn, the tibia will feel unrestrained in the degree
      to which it can move forward.

Simmulated Torn ACL–Note How Far The Tibia Is Distracted Relative To The Femur

  1. Compare this to the other side by simply shifting your hands to the same
    position on the opposite leg and repeating.

Anterior Drawer Test Positive Anterior Drawer Test

Posterior Cruciate (PCL)

Posterior Drawer Test

    1. Have the patient lie down, with the right knee flexed such that their foot
      is flat on the table.
    2. Gently sit on the foot. Grasp below the knee with both hands, with your
      thumbs meeting along the front of the tibia.
    3. Gently push backward, gauging how much the tibia moves in that direction
      in relation to the femur. The intact PCL will give a discrete end point.

Stressing the PCL (Because Of Its Posterior Location, The Actual Ligament Cannot Be Seen In Picture On Right)

    1. Compare this to the other side by simply shifting your hands to the same
      position on the opposite leg and repeating.
    2. If the PCL is completely torn, the tibia will feel unrestrained in the
      degree to which it moves backwards.

Simmulated Torn PCL–Note How Far Back The Tibia Moves Relative To The Femur

  1. If the PCL is completely torn, the tibia may appear to “sag” backwards
    even before you apply any force.

Posterior Drawer Test

Assorted Other Testing

Patello-Femoral Syndrome: A problem with the way in which the patellar
articulates with the femur and moves (tracks) during flexion and extension.
As a result, cartilage lining the undersurface of the patella becomes irritated
and worn down. Known as Chondromalacia, this process causes anterior knee pain
with activity and often after prolonged sitting. Several ways of assessing for
this condition are described below:

  1. Have the patient slightly flex the leg to be tested.
  2. Gently push down on the patella with both thumbs, which may elicit pain
    in the setting of Chondromalacia.
  3. Now, gently move the patella from side to side and try to palpate its undersurface.
    This may elicit pain in the setting of Chondromalacia.
  4. Hold the patella in place with your hand and ask the patient to contract
    their quadriceps muscle. This will force the inferior surface of the patella
    onto the femur, eliciting pain in the setting of Chondromalacia.

Assessing For Chondromalacia

Bursitis

Bursa are small pouches of fluid that lie between bony prominences and the
tendons that surround joints. Their presence allows the tendons to move without
generating a lot of friction. The bursa do not communicate with the joint space
itself. Inflammation of the bursa, most commonly due to overuse of the tendon
or direct trauma, can cause pain and swelling. Examination of the affected area
reveals focal pain. Swelling, warmth, and redness may be prominent if there
is concurrent infection, another cause of bursitis. Bursitis can be distinguished
from an intra-articular process because of the location of the pain and the
fact that movement of the joint itself does not cause discomfort. The major
bursa surrounding the knee include:

  1. Pre-patella: Located directly
    on top of the patella. Most frequently affected due to direct trauma, as may
    occur with people who spend a lot of time on their knees (e.g. carpet layers,
    carepenters).
  2. Infrapatella (a.k.a. anserine): Below the knee. Also affected by direct
    trauma, as with the prepatella bursa.

Location Of Bursa Is Shown On Model (Left). Picture On Right Demonstrates Septic Prepatellar Bursitis Of The Left Knee.


Adapted, with permission from University of California, San Diego School of Medicine By Charlie Goldberg, M.D.

Jump to: Top of the Page